// Copyright (C) 2002-2003

// David Moore, William E. Kempf

// Copyright (C) 2007-8 Anthony Williams

//

//  Distributed under the Boost Software License, Version 1.0. (See accompanying 

//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_BARRIER_JDM030602_HPP

#define BOOST_BARRIER_JDM030602_HPP

#include <boost/thread/detail/config.hpp>

#include <boost/thread/mutex.hpp>

#include <boost/thread/condition_variable.hpp>

#include <string>

#include <stdexcept>

#include <boost/config/abi_prefix.hpp>

namespace boost

{

    class barrier

    {

    public:

        barrier(unsigned int count)

            : m_threshold(count), m_count(count), m_generation(0)

        {

            if (count == 0)

                throw std::invalid_argument("count cannot be zero.");

        }

        bool wait()

        {

            boost::mutex::scoped_lock lock(m_mutex);

            unsigned int gen = m_generation;

            if (--m_count == 0)

            {

                m_generation++;

                m_count = m_threshold;

                m_cond.notify_all();

                return true;

            }

            while (gen == m_generation)

                m_cond.wait(lock);

            return false;

        }

    private:

        mutex m_mutex;

        condition_variable m_cond;

        unsigned int m_threshold;

        unsigned int m_count;

        unsigned int m_generation;

    };

}   // namespace boost

#include <boost/config/abi_suffix.hpp>

#endif